Auxiliary lift attachment for a lifting device



United States Patent [54] AUXILIARY LIFT ATTACHMENT FOR A LIF'IINGDEVICE 10 Claims, 7 Drawing Figs.

[52] US. Cl. 214/315 [51] Int. Cl. 865g 65/34 [50] Field ofSearch214/315, 3 i 6, 317, 307

{56] References Cited UNTTED STATES PATENTS 2,678,743 5/1954 Backofen etal 214/317 Primary Examiner-Hugo O. Schulz Attorney-McCormick, Pauldingand Huber ABSTRACT: An auxiliary lift attachment is disclosed for usewith a lifting device such as a fork lift truck used to lift and handlea dump box of the type having a lifting lug extending rearwardly fromits rear wall. The lift attachment comprises a vertical track member anda lifting member movable along such track for engaging and raising thelift lug of a box carried by the lifting device. Raising movement of thelifting member is obtained from the normal lifting movement of thelifting device carriage and by means of a flexible member having one endattached to the lifting member and passing upwardly over a wheel at theupper end of the track member, the other end of such flexible memberbeing connected to the stationary vertical mast of the lifting device.

PATENTED nc22 I570 SHEET 3 0F 3 FIG. 3

INVENTOR WILLIAM E. HOWARD BY I Wc I ATTORN EYS AUXILIARY LIFTATTACHMENT FOR A LIFI'ING DEVICE BACKGROUND OF THE INVENTION Thisinvention relates to lifting devices, such as fork lift trucks, used topick up, lift and transport from place to place various articles, anddeals more particularly with an attachment for such a lifting deviceto'adapt it to use in picking up and dumping dump boxes.

The lifting attachment of this invention is particularly well adaptedfor use in connection with bottom dump boxes such as are supplied byvarious manufacturers in generally standard sizes and constructions.These boxes conventionally consist of a rectangular top body providingfour vertical sidewalls and open its top and bottom, and a bottom memberhinged at one end to the top body and nonnally closing the bottomthereof. The bottom carries feet for supporting the box from a floor andwhen the box is resting on its feet, the weight of the top bodymaintains it closed on the bottom member. A lifting lug is, however,provided on the rear wall of the top body and by pulling up on thislifting lug the rear end of the box may be raised to allow the front endof the bottom to move away from the front end of the top body and todump the contents of the box through the space so provided.

These dump bottom boxes are conventionally designed for and intended tobe handles handled by a fork lift truck and various auxiliary liftattachments have, in the past, been provided for use with fork lifttrucks for dumping such boxes. In the use of such an auxiliary liftequipped fork lift truck, the prongs of the truck are used to pick upand transport the boxes from place to place and when it is desired todump a box, the lifting member of the auxiliary lift attachment israised vertically relative to the prongs to engage and raise the liftinglug on the rear wall of the box, this resulting in the rear end of thebox being moved upwardly relative to the prongs to cause the desireddumping. The auxiliary lift attachments provided in the past, however,have been relatively complicated and expensive devices powered byhydraulic motors and the like and requiring separate controls. Thegeneral object of this invention is, therefore, to provide a relativelysimple, easily constructed, auxiliary lift attachment the foregoinggeneral type which attachment utilizes the normal raising movement ofthe lift carriage to achieve the raising movement of its lifting member,thereby eliminating the need for any additional hydraulic motors or thelike.

Since the auxiliary lift attachment of this invention is particularlywell adapted for use with fork lift trucks and in connection with thehandling of bottom dump boxes, it has been shown and described herein inconnection with such items. It should be understood, however, that theinvention is not necessarily limited to such use with these particularitems. More particularly, it may be used with other types of liftingdevices other than fork lift trucks, such as a manually powered lift orany lift device having a generally vertical mast and a lifting carriagemovable vertically relative to such mast and including a horizontallyextending support means for engaging the bottom of an article to belifted. Also, the lifting attachment is not limited to use with bottomdump boxes but may be also used with other types of dump boxes such asfront dump boxes wherein the front wall of the box is swingableoutwardly away from the remainder of the box to provide a dumping gate.

SUMMARY OF THE INVENTION This invention resides in an auxiliary liftattachment for use with a lifting device, such as a fork lift truck,used to lift dump boxes and including a vertical mast and a liftingcarriage movable vertically on the mast and having a generallyhorizontally extending support means, such as a pair of prongs, attachedthereto for engagement with the bottom of a box for lifting such box asthe carriage is raised. The attachment comprises a vertical track memberand a lifting member movable vertically thereof. The lilting memberextends forwardly from the track member and is arranged to engage thelining lug of a box carried by the prongs or other support means of thelifting device as the lifting member is raised. Raising movement of thelifting member is obtained by a flexible tension member having one endconnected to the lifting member and passing upwardly therefrom and overa wheel rotatably supported at the upper end of the track member. Theother end of the flexible member is connected to the mast of the liftingdevice by means which prevent it from moving upwardly beyond a givenvertical limit. Therefore, as the lifting carriage and attached trackmember is moved upwardly beyond the point at which the other end of theflexible tension member reaches its vertical limit, the tension memberis pulled over the wheel to raise the lifiing member relative to thetrack member. Adjustment means are provided for adjusting the. upperlimit of movement of the other end of the flexible member so as tocontrol the point at which the lifting member starts to move thereforeand the level at which the dump box carried by the prongs or othersupport means is dumped.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of a forklift truck equipped with an auxiliary lift attachment embodying thisinvention, the lifting carriage of the fork lift truck in this viewbeing shown raised to a position at which the lifting member of the liftattachment is raised to its box dumping position.

FIG. 2 is a side view of the apparatus shown in FIG. 1, but with thelifting carriage of the fork lift truck being shown in its loweredposition.

FIG. 3 is a view similar to FIG. 2 but shows the lifting carriage raisedto the point at which the lifting member of the auxiliary liftattachment is raised to a box dumping position.

FIG. 4 is a vertical sectional view taken through the track member ofthe auxiliary lift attachment of FIG. 1, this view showing the liftingmember in its lowered position.

FIG. 5 is an enlarged horizontal sectional view taken on the line 5-5 ofFIG. 4.

FIG. 6 is an enlarged horizontal sectional view taken on the line 6-6 ofFIG. I.

FIG. 7 is a fragmentary rear view taken on the line 7-7 of FIG. 2 andshowing the upper end of the track member and the associated crossbar.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning to the drawings andfirst considering FIG. 1, this FIG. shows a lifting device in the formof a fork lift truck 10. This truck 10 is of generally conventionalconstruction and includes a vertical mast I2 having two laterally spacedmembers 14, 14, these members being fixed against vertical movementrelative to the remainder of the truck. A lifting carriage 16 issupported for vertical movement relative to the mast 12 and is poweredby a hydraulic cylinder 18 controlled by the operator of the truck. Thecarriage 16 includes two horizontal plates 20 and 22, which arevertically spaced from one another, and a horizontally extending rod 24located above the upper plate 22. The rod 24 vertically supports twoforks 26, 26. Each fork 26 in turn includes a horizontally extendingprong 28 and a vertically extending arm 30 with the upper end of the armbeing apertured and slidably received on the rod 24 as shown. The weightof the forks, therefore, causes the arms 30, 30 to bear against thecarriage plates 20 and 22 and the forks are slidable laterally along therod 24 to vary the spacing therebetween to adjust them to the spacingrequired for the particular load to be picked up, the horizontal prongs28, 28 comprising horizontally extending support means for engaging thebottom surface of an article for raising and lifting the same.

Still referring to FIG. I, an auxiliary lift attachment embodying thisinvention is there indicated generally at 32. This lift attachmentincludes a track defining means in the form of a track member 34attached to the carriage 16 between the forks 26, 26 with itslongitudinal axis generally vertical. Movable vertically along the trackmember 34 is a lifiing member 36 which is'engageable with the liftinglug of a dump box, not shown in FIG. 1, for raising the rear end of suchbox relative to the prongs 28, 28 to achieve dumping of the same. Asexplained hereinafter, the movement of the lifting member 36 relative tothe track member 34 is coordinated with and caused by the normal raisingmovement of the carriage l6, and in FIG. 1 the carriage I6 is shown at alevel at which the lifting member 36 is raised to its dumping positionrelative to the track member 34.

The construction of the auxiliary lift attachment is best shown in FIGS.4, 5, 6 and 7 and in referring to these FIGS. it will be noted that thetrack member 34 is a tubular member of generally square cross sectionand includes a slot 38 in its front wall extending from the bottom ofthe member 34 for a substantial distance along the length thereof. Thelifting member 36, in turn, is in the form of a trolley having a set ofwheels 40, 40 located inside of the member 34 and engageable with theinside surface of said member so as to be capable of rolling in thevertical direction therealong. Preferably, these wheels are or includeantifriction bearings so as to reduce the effort required to raise thelifting member 36. As shown in FIGS. 4 and 5, the lifting memberprojects through the slot 38 and beyond the track member 34 and has aforward portion 42 having a flat forwardly directed face 44. This face44 is used to engage the rear wall of a dump box as the prongs 28, 28are moved into underlying relation with the box and serves to properlyposition the box on the prongs so as to ensure proper engagement of thelifting member 36 with the lifting lug of the box as the lifting member36 is raised relative to the track member 34.

The means used for attaching the track member 34 to a lifting carriagemay vary widely, but where the lifting carriage is of the constructionshown in FIG. I, such means preferably comprises, as best shown in FIGS.4 and 6, a hook 46 welded to the rear wall of the track member 34 andadapted to hook over the top edge of the top carriage plate 22, a spacerplate 48 also being welded to the rear wall of the track member 34 tospace the track member a proper distance forwardly from the plate 22.Another part of the attachment means consists of a horizontal bar 50welded to another spacer plate 52 which spacer plate 52 is in turnwelded to the rear wall of the track member 34. The spacer plate 52spaces the track member a proper distance forwardly from the bottomcarriage plate 20 and the horizontal bar 50 rests on the top edge of theplate 20, it being located in the space between the two carriage plates22 and 20.

As shown best in FIGS. 1 and 6, the bar 50 extends laterally to eitherside of the track member 34 and each laterally extending portion thereofextends behind the vertical arm 30 of the adjacent fork 26. The two forkarms 30, 30, therefore, prevent the bar from moving forwardly and theengagement of the spacer plate 52 with the plate 20 prevents it frommoving rearwardly, the bar 50, therefore, being effectively locked inplace by the plate 20 and arms 30, 30. The bar 50 is, however, of such alength that when the prongs 26, 26 are moved to their extreme outerpositions, as shown by the broken lines in FIG. 6, by sliding along therod 24, the vertical anns 30, 30 of the prongs are positioned free ofbar 50 so that the bar may be removed from its place between thecarriage plates 20 and 22, therefore, allowing the lifting attachment tobe readily attached to or removed from the carriage simply by moving theprongs 26, 26 between the two positions illustrated in FIG. 6. Further,the bar 50 preferably includes two forwardly projecting stops 54, 54attached respectively to the two laterally extending portions thereofwith each stop being engageable with the respective one of the fork arms30, 30 as shown. The stops 54, 54 are further so spaced from one anotherthat when the arms 30, 30 are brought into engagement therewith theprongs 26, 26 are spaced a proper distance from one another for use inhandling the dump boxes in question.

Referring to FIGS. 4 and 7, the lifting member 36 is moved relative tothe track member by a flexible tension member in the form of a rollerchain 56 having one end attached, as at 58, to the upper end of thelifiing member 36. From the attachment point 58, the chain 56 passesupwardly through the track member 34 and passes over a toothlesssprocket wheel 60 which is rotatably supported at the upper end of thetrack member 34 for rotation about a horizontal axis parallel to thecarriage I6 by a shaft 62. Attached to the other end of the chain 56, asat 64, is a crossbar 66 which extends laterally outwardly beyond bothsides of the track member 34 and is connected to the two verticalmembers 14, I4 of the lift truck mast 12 in such a manner that it isprevented from moving upwardly beyond a given vertical limit relative tothe mast.

The means for so connecting the crossbar to the vertical mast member 14,14 may vary but in the present instance is shown to consist of twoadditional flexible tension members in the form of chains 68, 68 eachhaving one end attached to a respective end of the crossbar and havingits other end connected to a hook 70 welded to the upper end of theassociated mast member 14, as shown in FIG. 1. In FIG. 1, only the hook70 attached to the left-hand vertical member 14 is shown, but it shouldbe understood that a similar hook is also provided on the right-handvertical member 14 at a corresponding height. Each vertical mast memberl4 also has fixed thereto by welding or the like a number of verticallyspaced laterally outwardly extending headed adjustment posts 72, 72, asshown on the left-hand vertical member 14 of FIG. I, it being understoodthat the left-hand vertical member 14 includes a similar set of suchposts 72, 72 at corresponding levels. Each chain 68 is of such a lengththat it extends downwardly from the crossbar 66, around one of theassociated set of adjustment posts 72, 72 and upwardly to its associatedhook 70. The particular adjustment post about which each chain passes isselected by the operator to control the height at which the box carriedby the prongs 28, 28 is dumped, as hereinafter explained.

Having now explained the construction of the auxiliary lift attachmentof this invention, its operation may be more fully appreciated byconsidering FIGS. 2 and 3. Referring to these figures, a bottom dump boxof the type with which the lift attachment may be used is shown inbroken lines at 74 and includes a lug body member 76 having an open topand an open body, and a bottom member 78 which normally closes thebottom of the top member 76 and which includes legs 80, 80 for normallysupporting the box a small distance above the floor on which it rests.The bottom member 78 is connected to the top member 76 for swingingmovement about a hinge axis indicated at 82 located near and extendingalong the bottom rear edge of the top member 76. A rearwardly extendinglifting lug 84 is attached to the rear wall 85 of the top member 76.

In FIG. 2, the carriage 16 of the fork lift truck 10 is shown lowered tothe position at which the prongs 28, 28 may be moved horizontallyunderneath the box 74 to bring them into proper position beneath the boxto thereafter raise the same. In moving the prongs to this position, thefork lift truck is moved forwardly toward the rear wall 85 of the boxuntil the forward face 44 of the lifting member engages such wall.Thereafter, the carriage 16 is raised to raise the prongs 28, 28 therebybringing the prongs into engagement with the bottom of the dump box andlifting it off the floor. With the box so lifted the truck 20 may bedriven to any location to transport the box from one place to another.Generally for such transport from place to place, the carriage I6 israised only a small amount which is not sufiicient to cause any raisingmovement of the lifting member 36. When, however, it is desired to dumpthe box 74, the carriage I6 is raised to a still higher elevation andduring such raising movement it eventually comes to a point at which allof the slack is taken up in the chains 68, 68 so that further upwardmovement of the crossbar 66 is prevented. Therefore, as the carriage israised still further above this limit, such raising movement willthereafter cause the chain 56 within the track member 34 to move overthe wheel 60 and thereby raise the lifting member 36 relative to thetrack member 34. As the lifting member 36 so moves along the track 34,it eventually engages the lifting lug 84 of the box 74 and as a resultof such engagement and further upward movement raises the rear end ofthe box 74 and the attached rear end of the bottom member 78. Since thefront end of the bottom member 78 is unattached to the body 76, thisfront end will notmove upwardly with the body 76 with the result thatthe froht end of the bottom 78 moves away from the body 76 to theposition shown in FIG. 3 at which the contents of the box are dumped bysliding along the bottom member 78 and off the front edge thereof. Ofcourse, at the time this dumping occurs, the fork truck will have beenmoved to position the box 74 above a bin, truck body, or otherreceptacle into which it is desired to dump the box contents. After thecontents of the box are dumped, the carriage 16 is lowered, thislowering movement of the carriage lowering the lifting member 36 andreturning the box to its closed position.

I claim:

1. An auxiliary lift attachment for a lifting device used to lift a dumpbox of the type having a lifting lug extending rearwardly from its rearwall and, which lifting device includes a generally vertical mast, acarriage movable vertically relative to said mast, and a generallyhorizontally extending support means on said carriage engageable withthe bottom of such a box to lift it as said carriage is raised, saidauxiliary lift attachment comprising means defining an elongated track,means for attaching said track defining means to a carriage such asaforesaid with its longitudinal axis extending generally vertically, alifting member supported by said track defining means for verticalmovement relative thereto, a wheel at the upper end of said trackdefining means and supported for movement relative thereto about ahorizontal axis, a main flexible tension member having one end attachedto said lifting member and extending upwardly therefrom and trained oversaid wheel, and means for connecting the other end of said flexibletension member to said mast to prevent it from moving upwardly beyond agiven vertical limit as said carriage is raised so that as said carriageis raised beyond the point at which such other end of said flexibletension member reaches said vertical limit said flexible tension memberis pulled over said wheel to raise said lifting member relative to saidtrack defining means, said lifting member having a forward portion whichis engageable with the lifting lug of a dump box such as aforesaidpositioned in a normal manner on said support means so as to lift saidlug and said box relative to said support means as a result of saidraising movement of said lifting member.

2. An auxiliary lift attachment as defined in claim 1 furthercharacterized by means for adjusting said vertical limit beyond whichsaid other end of said flexible tension member is prevented from movingupwardly so as to thereby adjust the level of said carriage at whichsaid lifting member engages and start to rise the lifting lug of a boxcarried by said support means.

3. An auxiliary lift attachment as defined in claim 1 particularlyadapted for use with a lifting device in the nature of a fork lift truckwherein said carriage includes two horizontally extending verticallyspaced plates" and said generally horizontally extending support meanscomprises two fork members each having a horizontally forwardlyextending prong and a vertically extending arm which arm bears againstthe forward faces of said two carriage plates and is slidable laterallyrelative thereto to vary the spacing between said prongs, said liftingdevice being further characterized by said attachment means forattaching said track defining means to said carriage comprising a hookfixed to said track defining means and adapted to hook over the top edgeof the upper one of said two carriage plates, and a horizontal bar fixedto said track defining means and extending laterally from either sidethereof which bar is adapted to reside in the space between said twocarriage plates and to rest on the top edge of the lower one of said twocarriage plates with each laterally extending portion of said bar havinga part thereof positioned behind an associated one of said vertical forkarms.

4. An auxiliary lift attachment as defined in claim 3 furthercharacterized by each of said laterally extending portions of said barincluding a forwardly extending stop for engaging the associated one ofsaid vertical fork arms to limit the movement of said arm toward theother one of said arms, the two of said stops therefor establishing aminimum spacing for said fork arms and their associated prongs.

5. An auxiliary lift attachment as defined in claim 1 furthercharacterized by said track defining means comprising an elongatedtubular member having a slot in its forward wall extending along aportion of the length thereof, and said lifting member comprising atrolley having a set of wheels located within said tubular member andengageable with the inside surface thereof for vertical rolling movementtherealong, said trolley also including a portion projecting forwardlythrough said slot and beyond said tubular member for engagement with thelifting lug of a dump box positionedon said associated support means.

6. A lifting attachment as defined in claim 5 further characterized bysaid portion of said trolley which extends forwardly beyond said tubularmember including a forwardly facing face for engagement with the rearwall of a dump box such as aforesaid to limit the rearward movement ofsaid box relative to said support means as said support means is movedforwardly into underlying relation with the bottom of such box.

7. A lifting device as defined in claim 1 for use with a lifting devicewherein said mast includes two laterally spaced vertical members fixedagainst vertical movement, and wherein said lifting attachment isadapted to be attached to said carriage with said track defining meansbeing located between said two mast members, said lifting attachmentbeing further characterized by said means for connecting said other endof said main flexible tension member to said mast to prevent it frommoving upwardly beyond a given vertical limit comprising a crossbarfixed to said other end of said flexible tension member and extendinglaterally in both directions from said track defining means, and twoadditional flexible tension members each connected between a respectiveone of the ends of said crossbar and an associated one of said twovertical mast members.

8. A lifting attachment as defined in claim 7 further characterized by aplurality of laterally outwardly extending adjustment posts fixed toeach of said two vertical mast members over which posts said twoadditional flexible tension members may be selectively looped toadjustably vary said vertical limit beyond which said other end of saidmain flexible tension member is prevented from moving upwardly, each ofsaid two additional flexible tension members having its mast connectedend connected to its associated vertical mast member at a level abovesaid laterally extending adjustment posts so as to normally extenddownwardly from such attachment point, around one of said adjustmentposts and upwardly to said crossbar.

9. An auxiliary lift attachment as defined in claim 1 particularlyadapted for use with a lifting device wherein said generally verticalmast includes two laterally spaced vertical members fixed againstvertical movement, and wherein said track defining means is adapted tobe attached to said carriage between said two vertical mast members,said lift attachment being further characterized by said track definingmeans comprising an elongated tubular member having a slot in its forward wall extending along a portion of the length thereof, said liftingmember comprising a trolley including a set of wheels located withinsaid tubular member and engageable with the inside surface thereof forrolling movement vertically thereof, said trolley also including aportion extending forwardly through said slot and beyond said tubularmember for lifting engagement with the lug of a dump box positioned onsaid support means, and said means for connecting the other end of saidflexible tension member to said mast to prevent it from moving upwardlybeyond a given vertical limit comprising a crossbar and an associatedone of said mast members.

10. A lifting device as defined in claim 9 further characterized by saidtubular member being of a generally square cross section.

